Lawyers for Boston Marathon bombing suspect Dzhokhar Tsarnaev are again asking a federal judge to lift special restrictions that have been placed on their client, saying they are impeding the defense.

The lawyers said in a court filing Thursday that the FBI has been monitoring the case and that the Bureau of Prisons has tried to screen digital documents they have tried to view with Tsarnaev, in violation of his constitutional rights to prepare his case without government interference.

The restrictions "threaten the integrity of attorney work product," the lawyers said.

Defense lawyers previously asked U.S. District Court Judge George O'Toole Jr. in October to ease the restrictions. Prosecutors lifted some.

Prosecutors say the restrictions are necessary due to the suspect's "commitment to jihad" and "widespread notoriety."